1. Field of the Invention
The present invention relates to a film useful in various applications of polarizer protective films and the like, and its production method, and to a polarizer and a liquid crystal display device using the film.
2. Description of the Related Art
The surface of the viewers' side polarizer for use in display devices such as liquid crystal display devices and others is required to be given various functions of scratch resistance, antireflection, static elimination, etc. As the method for giving the functions, a general method is known, which comprises forming a functional layer such as a curable layer or the like of an active energy ray-curable composition on the surface of the protective film of a polarizer. However, the method has a problem in that the adhesiveness between the surface of the cellulose acylate film generally used as the protective film and the curable layer to be formed thereon is poor. Patent Reference 1 proposes a cellulose acylate film having solved the problem, in which the adhesiveness of the film to the functional layer such as the active energy ray-curable layer or the like has been enhanced.
Regarding liquid crystal display devices, the frequency of outdoor use thereof centering on digital signboards and others is expected to increase in future; and liquid crystal display devices capable of enduring use thereof even in severer environments than before are desired. In liquid crystal display devices, widely used is a polarizer in which the polarizing element formed of polyvinyl alcohol (PVA) and iodine is sandwiched between polarizer protective films of cellulose acylate films, etc. The polarizing element formed of PVA and iodine has a weak point in that its polarization performance may often worsen in high-temperature high-humidity environments, and for satisfying the requirements in outdoor use, the polarizing element of the type must be further improved. In addition, for outdoor use, the above-mentioned functional layers are also required to have further more enhanced durability than those for indoor use. Above all, stability to light is an especially important factor; however, the conventional functional layers have a problem in that the active energy ray-curable layer may peel away from the cellulose acylate film when exposed to light for a long period of time, and in these, therefore, even though the initial adhesiveness could be improved, the light-resistant adhesiveness could not still be improved.
As a means for enhancing the light resistance of resin films, in general, a UVabsorbent and an antioxidant may be added thereto. For example, Patent Reference 2 discloses a resin film with a triazine-type UV absorbent and a hindered amine-type antioxidant added thereto. Patent Reference 3 and Patent Reference 4 disclose a cellulose acylate film containing a hindered amine-type antioxidant.
Patent Reference 1: JP-A 2011-116113
Patent Reference 2: JP-A 2009-167416
Patent Reference 3: WO07/072,643
Patent Reference 4: JP-A 2006-123513